Chapter 16 Laboratory Assessment Nutritional Significance

The serum glucose level is a test used to diagnose many metabolic diseases. Serum glucose levels must be ele- vated at different times of day for an accurate diagnosis. There are several factors, including stress, infection, caf- feine, and smoking, that can elevate fasting blood glucose levels. Elevated blood glucose levels often give falsely low serum sodium values (1). One formula to correct serum sodium values is as follows:

Corrected Na = [(Glucose/6) × 2] + Measured Na

The most common diagnosis associated with an elevated blood glucose level is diabetes mellitus. A fasting blood glucose test is performed on serum or plasma rather than on whole blood. Values will likely vary from the whole-blood glucose tests performed on capillary blood using the finger-stick method. Laboratory values using whole blood are likely to be 10% to 15% higher than capillary values (5). In the 2014 Standard of Medical Care in Diabetes

(4), the diagnostic criteria for diabetes are as follows: ●

A1C ≥ 6.5% OR ●

fasting plasma glucose (FPG) ≥ 126 mg/dL (7 mmol/L)

OR ●

2-h plasma glucose (PG) ≥ 200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test (OGTT)

OR ●

in a patient with classic symptoms of hyperglyce- mia or hypoglycemic crisis, a random plasma glucose ≥ 200 mg/dL (11.1 mmol/L)

Diabetes is seen in about 10% of the clients older

than 65 years (4). There are currently no long-term studies to demonstrate the benefits of tight glycemic control in older adults. Individuals who are active, cog- nitively intact, and expect to live 10 to 20 years should be encouraged to control the disease process with diet, exercise, and medications. Individuals with advanced diabetes complications, other comorbidities, or cogni- tive or functional impairments are less likely to benefit from tight glycemic control. Reasonable glycemic goals for these individuals are fasting glucose lower than 140 mg/dL and postprandial glucose lower than 200 to 220 mg/dL (4).

● ● ●

Blood glucose levels increase with (1): diabetes

cystic fibrosis

Cushing syndrome (due to increased glucocorticoids)

● ● ●

hyperthyroidism pituitary adenoma acute pancreatitis

● adenoma of pancreas ●

●

dehydration, stress, trauma chronic liver disease ● hemochromatosis general anesthesia

● ● cerebral vascular accident (CVA) ● MI

Blood glucose levels decrease with (1): ●

● ● ● ● ● ● ●

liver disease poisoning hepatitis cirrhosis

metastatic tumor

pancreatic disorders glucagon deficiency islet cell carcinoma ● enzyme diseases

● Von Gierke’s disease galactosemia

●

● maple syrup urine disease fructose intolerance endocrine disorders Addison’s disease hypothyroidism water overload insulin overdose alcoholism

● ● ● ● ● ● ●

The following drugs may increase blood glucose levels (1): ●

● ● ● ● ● ● ● ● ● ● ●

antidepressants beta-blockers caffeine

borticosteroids dextrothyroxine diazoxide diuretics

epinephrine estrogen isoniazid lithium

pentamidine

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